Image pickup apparatus and method for controlling the same

ABSTRACT

According to the present invention, an image pickup apparatus includes, an image pickup control unit which drives shutter unit and picks up a still image by image pickup device, captures a first through image by the image pickup device when the shutter unit is opened, and picks up a second through image including a light-shielded area by the image pickup device, the light-shielded area being formed by shielding part of light incident upon imaging plane by the shutter unit when the shutter unit is half light-shielded, and a display control unit which causes a display device to display a through image using at least the first through image and the second through image.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 15/138,932 (referred to as “the '932 application” andincorporated herein by reference), filed on Apr. 26, 2016, titled “IMAGEPICKUP APPARATUS AND METHOD FOR CONTROLLING THE SAME TO PREVENT DISPLAYOF A THROUGH IMAGE FROM BEING STOPPED WHEN A SHUTTER UNIT IS NOTCOMPLETELY OPENED” and listing Takayuki MATSUHASHI, Haruyuki ISHIHARA,Ryosuke MOCHIZUKI and Mika MUTO as the inventors, the '932 applicationbeing based upon and claiming the benefit of priority from priorJapanese Patent Applications No. 2015-094380, filed May 1, 2015, No.2015-094381, filed May 1, 2015 and No. 2015-094382, filed May 1, 2015,the entire contents all of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to an image pickup apparatus and a methodfor controlling the same.

2. Description of the Related Art

Image pickup devices generally include an image pickup device forpicking up an image based upon light, an optical system, such as a lens,for forming an image of the light on the image pickup device, a shutterfor controlling time when light is incident upon the image pickup devicethrough the optical system, and a display device for displaying theimage picked up by the image pickup. For example, Jpn. Pat. Appln. KOKAIPublication No. 2009-260510 proposes an image pickup apparatus whichallows a user to confirm an object by displaying a through image todisplay images picked up by the image pickup apparatus one by one.

BRIEF SUMMARY OF THE INVENTION

An image pickup apparatus as described above performs an image-pickupoperation of stopping picking up a through image and operating a shutterto pick up a still image. When exposure is completed, the shutter isopened to resume picking up the through image. The image pickupapparatus cannot pick up a through image to darken display of thethrough image with timing when the shutter is not completely openedafter the exposure is completed. Thus, the image pickup apparatus hasthe problem that a user is likely to lose sight of an object and thedevice is likely to be inconvenient.

It is therefore an object of the present invention to provide a moreconvenient image pickup apparatus and a method for controlling the same.

Advantages of the invention will be set forth in the description whichfollows, and in part will be obvious from the description, or may belearned by practice of the invention. The advantages of the inventionmay be realized and obtained by means of the instrumentalities andcombinations particularly pointed out hereinafter.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate embodiments of the invention, andtogether with the general description given above and the detaileddescription of the embodiments given below, serve to explain theprinciples of the invention.

FIG. 1 is a block diagram illustrating an example of a control system ofan image pickup apparatus according to one embodiment.

FIG. 2 is an illustration of an example of the outward appearance of theimage pickup apparatus according to one embodiment.

FIG. 3 is an illustration of an example of the configuration of aportion close to a shutter unit of the image pickup apparatus accordingto one embodiment.

FIG. 4 is an illustration of an example of operation of the image pickupapparatus according to one embodiment.

FIG. 5 is a timing chart showing an example of operation of the imagepickup apparatus according to one embodiment.

FIG. 6 is an illustration of an example of display of the image pickupapparatus according to one embodiment.

FIG. 7 is an illustration of another example of display of the imagepickup apparatus according to one embodiment.

FIG. 8 is an illustration of still another example of display of theimage pickup apparatus according to one embodiment.

FIG. 9 is an illustration of yet another example of display of the imagepickup apparatus according to one embodiment.

FIG. 10 is a flowchart showing an example of operation of the imagepickup apparatus according to one embodiment.

FIG. 11 is a flowchart showing another example of operation of the imagepickup apparatus according to one embodiment.

FIG. 12 is a flowchart showing still another example of operation of theimage pickup apparatus according to one embodiment.

FIG. 13 is a flowchart showing yet another example of operation of theimage pickup apparatus according to one embodiment.

FIG. 14 is an illustration of another example of display of the imagepickup apparatus according to one embodiment.

FIG. 15 is an illustration of still another example of display of theimage pickup apparatus according to one embodiment.

DETAILED DESCRIPTION OF THE INVENTION

An image pickup apparatus and a method for controlling the image pickupapparatus according to one embodiment will be described in detail belowwith reference to the accompanying drawings.

As illustrated in FIGS. 1 and 2, an image pickup apparatus 1 includes alens 10, a shutter unit 11, an image pickup device 12, a signalprocessing unit 13, an image processing unit 14, an operation unit 15, adisplay unit 16, a memory I/F 17, an acceleration sensor 18, and a maincontrol unit 19, which are electrically connected to each other via databuses to allow different data items to be communicated.

The lens 10 is designed to transmit light and form an image of the lighton the image pickup device 12. The lens 10 includes an image pickup lensin which a plurality of lenses are combined, a diaphragm mechanism, alens control unit for controlling operations of the image pickup lensand the diaphragm mechanism, a focus ring, and a zoom ring.

The image pickup lens is designed to transmit a light ray from an objectand form an image of the light ray on the imaging plane of the imagepickup device 12. The image pickup lens includes a lens for focusing (afocus lens), a focal length varying lens (a variator lens and acompensator lens) and a relay lens. The image pickup lens moves thefocus lens in the optical axis direction of the image pickup lens underthe control of the lens control unit or by the operation of the focusring to form an image of the object on the imaging plane of the imagepickup device 12. The image pickup lens also moves the variator lens andthe compensator lens in the optical axis direction of the image pickuplens under the control of the lens control unit or by the operation ofthe zoom ring to change a focal length.

The diaphragm mechanism is so configured that it can freely be opened orclosed to adjust the amount of light that is incident upon the imagepickup device 12 through the image pickup device, under the control ofthe lens control unit.

The lens control unit is configured to communicate with the main controlunit 19. The lens control unit controls driving of the focus lens, thatof the variator lens and the compensator lens and that of the diaphragmmechanism in accordance with an input from the main control unit 19, anoperation of the focus ring and the operation of the zoom ring.Furthermore, the lens control unit is able to detect a focal length ofthe image pickup lens by detecting the positions of the variator lensand the compensator lens. The lens control unit supplies the detectedfocal length of the image pickup lens to the main control unit 19.

The shutter unit 11 is a mechanism for adjusting the amount of lightthat is incident upon the image pickup device 12 through the lens 10.The shutter unit 11 is, for example, a focal plane shutter. Asillustrated in FIG. 3, the shutter unit 11 is provided between the lens10 and the image pickup device 12 to bring an open state in which lightis incident upon the imaging plane of the image pickup device 12 throughthe lens 10 and a light-shielding state in which the imaging plane ofthe image pickup device 12 is shielded from the light transmittedthrough the lens 10. The shutter unit 11 includes a front curtain 21, arear curtain 22, and a shutter driving unit 23 for driving the front andrear curtains 21 and 22. The shutter driving unit 23 operates the frontand rear curtains 21 and 22 at speed and timing based upon a shutterspeed supplied from the main control unit 19 to adjust exposure timewhen light is incident upon the imaging plane of the image pickup device12 through the lens 10 and thus adjust the amount of light incident uponthe image pickup device 12.

In an image pickup standby state in which the image pickup apparatus 1is able to perform an imaging operation of recording a still image, theshutter unit 11 maintains an open state in which the front and rearcurtains 21 and 22 are completely open. The front curtain 21 is providedin the lower part of the shutter unit 11 and the rear curtain 22 isprovided in the upper part of the shutter unit 11. When an imagingoperation is carried out, the shutter unit 11 starts to close the frontcurtain from bottom to top. The shutter unit 11 brings asemi-light-shielding state in which the image pickup device 12 is partlylight-shielded by the front curtain 21, from when it starts to close thefront curtain 21 until it completely closes the front curtain 21. Whenthe front curtain 21 is completely closed, the shutter unit 11 starts toopen the front curtain 21 from top to bottom and close the rear curtain22 from top to bottom. In this case, light is incident upon the imagepickup device 12 through a slit formed between the front curtain 21 thatopens from top to bottom and the rear curtain 22 that closes from top tobottom. When the front curtain 21 completely opens and the rear curtain22 completely closes, the shutter unit 11 starts to open the rearcurtain 22 from bottom to top. The shutter unit 11 brings asemi-light-shielding state in which the image pickup device 12 is partlylight-shielded by the rear curtain 22, from when it starts to open therear curtain 22 until it completely opens the rear curtain 22. When therear curtain 22 is completely opened, the front and rear curtains 21 and22 are brought into an open state again and the image pickup apparatus 1is brought into an image pickup standby state. The shutter unit 11includes a sensor for sensing, e.g. an open/close state of each of thefront and rear curtains 21 and 22. If the sensor senses an open/closestate of each of the front and rear curtains 21 and 22, the shutter unit11 is able to detect whether it is in an open state or asemi-light-shielding state. The shutter unit 11 includes an opticalsensor such as a photocoupler or a magnetic sensor, as a sensor forsensing an open/close state of each of the front and rear curtains 21and 22.

The image pickup device 12 is provided behind the lens 10, or inside thecasing of the image pickup apparatus 1. The image pickup device 12 hasan imaging plane on which a plurality of imaging pixels, whichphotoelectrically convert light into electric charges and store theelectric charges, are arranged. A color filter is provided on theimaging plane upon which light of each of the imaging pixels isincident. The image pickup device 12 is configured by a charge coupleddevice (CCD) image sensor, a complementary metal oxide semiconductor(CMOS) image sensor or another image pickup device. The image pickupdevice 12 converts an object image, which is formed on the imaging planeby light collected through the lens 10, into an electrical signalcorresponding to the amount of light to generate an image signal.Furthermore, the imaging plane of the image pickup device 12 has aplurality of AF areas. In the AF areas, a plurality of imaging pixels, aplurality of first focusing pixels and a plurality of second focusingpixels are arranged. The first and second focusing pixels are restrictedby their different incident areas.

Like the imaging pixels, the first and second focusing pixelsphotoelectrically convert incident light into electric charges and storethe charges. The imaging plane of the image pickup device 12 is formedby, e.g. a plurality of imaging pixels arranged two-dimensionally. Thistwo-dimensional arrangement does not necessarily exclude an image pickupdevice having sensitivity in its depth direction or an image pickupdevice having pixels arranged randomly, but may include these imagepickup devices if they have at least pixels arranged on the plane. Acurved sensor whose imaging plane is curved to prevent aberration hasrecently been announced and includes pixels arranged two-dimensionally;thus, this sensor is referred to herein as one including pixels arrangedtwo-dimensionally in a broad sense.

The signal processing unit 13 reads an image signal captured by theimage pickup device 12 under the control of the main control unit 19.The signal processing unit 13 performs different processes for the readimage signal under the control of the main control unit 19. The signalprocessing unit 13 converts the processed image signal into image dataof a digital signal and supplies it to the main control unit 19.

The image data includes a still image and a through image. The stillimage represents image data captured by the image pickup device 12 inaccordance with the foregoing image pickup operation. The through imagerepresents image data captured continuously by the image pickup device12 when no image pickup operation is performed. For example, the signalprocessing unit 13 is able to capture continuous through images byreading through images picked up by the image pickup device 12 in acycle based on the control of the main control unit 19. The signalprocessing unit 13 reads a through image from the image pickup device 12in a cycle of 60 fps, 120 fps or the like.

The through image includes a first through image and a second throughimage. When the shutter unit 11 is opened, the signal processing unit 13captures a first through image in which the shutter unit 11 does notblock light transmitted through the lens 10. When the shutter unit 11 isrendered in a semi-light-shielding state, the signal processing unit 13captures a second through image including a light-shielded area wherethe rear curtain 22 of the shutter unit 11 blocks part of lighttransmitted through the lens 10.

The image processing unit 14 performs different image processings, suchas color correction, gamma (y) correction, contrast correction, blackand white/color mode processing and through-image processing, for imagedata under the control of the main control unit 19. Furthermore, theimage processing unit 14 compresses image data in JPEG format under thecontrol of the main control unit 19 and converts the compressed imagedata into JPEG data of JPEG-format image data. The image processing unit14 supplies the JPEG data to the main control unit 19.

The operation unit 15 includes a plurality of operation members by whicha user performs different operations of the image pickup apparatus 1.The operation members include a release button 15 a, a power button 15b, a recording button 15 c, a directional pad 15 d, an OK button 15 e, aplay button 15 f, a cancel button 15 g, a menu button 15 h, a firstoperation dial 15 i, a second operation dial 15 j and other differentbuttons.

The release button 15 a is an operation member for causing a user toprovide the image pickup apparatus 1 with an instruction for imagepickup operation and image pickup auxiliary control to pick up a stillimage. The image pickup auxiliary control is a process such as anautomatic exposure (AE) process and an automatic focusing (AF) process.The operation unit 15 provides the main control unit 19 with aninstruction for image pickup auxiliary control when the release button15 a is half pushed. The operation unit 15 also provides the maincontrol unit 19 with an instruction for image pickup operation to pickup a still image when the release button 15 a is all pushed.

The power button 15 b is an operation member for causing a user toprovide the image pickup apparatus 1 with an instruction to turn on oroff the image pickup apparatus 1.

The recording button 15 c is an operation member for causing a user toprovide the image pickup apparatus 1 with an instruction to start andfinish picking up a moving image.

The directional pad 15 d is an operation member for causing a user toprovide the image pickup apparatus 1 with an instruction to select anoperation corresponding to one of the left, right, top and bottomdirections. For example, the operation unit 15 provides the main controlunit 19 with an instruction to select an operation corresponding to oneof the left, right, top and bottom directions in the menu in accordancewith a user's operation of the directional pad 15 d. Furthermore, forexample, the operation unit 15 provides the main control unit 19 with aninstruction to move an automatic focusing (AF) area on the imaging planein accordance with a user's operation of the directional pad 15 d.

The OK button 15E is an operation member for causing a user to providethe image pickup apparatus 1 with an instruction for execution. The OKbutton 15E is located, for example, at the center of the directional pad15 d.

The play button 15 f is an operation member for causing a user toprovide the image pickup apparatus 1 with an instruction for play. Theoperation unit 15 provides the main control unit 19 with an instructionto play a still image or a moving image recorded on a recording mediumwhen a user operates the play button 15 f.

The cancel button 15 g is an operation member for causing a user toprovide an instruction for cancellation. The operation unit 15 providesthe main control unit 19 with an instruction to erase a still image or amoving image recorded on a recording medium when a user operates thecancel button 15 g.

The menu button 15 h is an operation member for causing a user toprovide the image pickup apparatus 1 with an instruction to display amenu screen.

The first and second operation dials 15 i and 15 j are each an operationmember for causing a user to provide the image pickup apparatus 1 withan instruction for exposure control. For example, the operation unit 15provides the main control unit 19 with an instruction to changeparameters for exposure control, such as a diaphragm value, a shutterspeed, ISO and an exposure value when a user operates the firstoperation dial 15 i or the second operation dial 15 j.

Furthermore, the operation unit 15 can be configured to include a touchsensor that is formed integrally with a display device of the displayunit 16. The touch sensor is, for example, a resistive touch sensor or acapacitive touch sensor. The operation unit 15 can be configured toreceive a signal from the touch sensor to perform an operationcorresponding to each of the operation members.

The display unit 16 displays a screen on the basis of image datasupplied from the main control unit 19. The display unit 16 includes adisplay device and a drive circuit for causing the screen to bedisplayed on the display device on the basis of the image data. Thedisplay unit 16 includes, for example, a display panel 31 and anelectronic view finder (EVF) 32 as the display device. The display unit16 also includes an eye sensor 33 for sensing whether a user looksthrough the EVF 32. The display panel 31 is configured by a liquidcrystal display, an organic EL display, a device for displaying anotherscreen, or the like. The EVF 32 includes, for example, a display devicesuch as a liquid crystal display and an organic EL display, and aneyepiece optical system.

When the eye sensor 33 senses that a user looks through the EVF 32, thedisplay unit 16 turns off the display panel 31 to cause the EVF 32 todisplay a screen. When the eye sensor 33 does not sense that a userlooks through the EVF 32, the display unit 16 turns off the EVF 32 tocause the display panel 31 to display a screen.

The memory I/F 17 includes a card slot into which a recording medium Mwith a plurality of contact terminals can be inserted and a contactterminal which is electrically connected to the contact terminals of therecording medium M when the recording medium M is inserted into the cardslot. The recording medium M is, for example, a memory card. The memoryI/F 17 relays data between the recording medium M and the main controlunit 19.

The acceleration sensor 18 senses a variation in acceleration of thecasing of the image pickup apparatus 1 to detect the inclination of thecasing of the image pickup apparatus 1. The acceleration sensor 18 alsosenses a variation in acceleration of the casing of the image pickupapparatus 1 to detect whether the lens 10 and casing of the image pickupapparatus 1 are panned or not. In other words, the acceleration sensor18 senses that a user follows an object by panning.

The main control unit 19 controls the operation of each unit of theimage pickup apparatus 1. The main control unit 19 includes, forexample, a CPU and a memory. The main control unit 19 fulfills differentfunctions if the CPU reads a program out of the memory and executes it.For example, the main control unit 19 serves as an operationdetermination unit 40, an image pickup control unit 41, an image pickupauxiliary control unit 42, a recording control unit 43, a displaycontrol unit 44 and a state determination unit 45.

The operation determination unit 40 determines an operation input by theoperation unit 15. In other words, the operation determination unit 40recognizes what operation is instructed by the operation unit 15.

Upon receipt of an instruction to perform an image pickup operation, theimage pickup control unit 41 controls each unit to perform the imagepickup operation. When the image pickup control unit 41 receives aninstruction to perform an image pickup operation, it inputs a controlsignal to the lens 10 to drive the diaphragm mechanism and also inputs acontrol signal to the shutter unit 11 to drive the front curtain 21 andthe rear curtain 22, thus performing an image pickup operation ofpicking up a still image. The image pickup control unit 41 generates acontrol signal which is to be input to the shutter unit 11 and the lens10 on the exposure conditions resulting from an operation or imagepickup auxiliary control of the image pickup auxiliary control unit 42.

Furthermore, the image pickup control unit 41 is able to perform imagepickup operations continuously. For example, when the image pickupcontrol unit 41 receives an instruction to perform image pickupoperations continuously, it inputs a control signal to the lens 10 todrive the diaphragm mechanism and operate the shutter unit 11continuously, thus performing a continuous image pickup operation ofperforming image pickup operations continuously. For example, the imagepickup control unit 41 switches between a mode (continuous image pickupmode) of performing a continuous image pickup operation and a mode ofnot performing a continuous image pickup operation in response to anoperation of the operation unit 15.

Furthermore, the image pickup control unit 41 controls a through imagepicked up by the image pickup device 12. For example, the image pickupcontrol unit 41 controls the signal processing unit 13 to read a throughimage picked up by the image pickup device 12 in a preset cycle. Theimage pickup control unit 41 controls the signal processing unit tocapture a first through image with timing when the shutter unit 11 isrendered in an open state. The image pickup control unit 41 alsocontrols the signal processing unit to capture a second through imagewith timing when the shutter unit 11 is rendered in asemi-light-shielding state.

The image pickup auxiliary control unit 42 performs image pickupauxiliary control prior to an image pickup operation. The image pickupauxiliary control unit 42 acquires information for image pickupauxiliary control and performs image pickup auxiliary control on thebasis of the acquired information. For example, the image pickupauxiliary control unit 42 performs image pickup auxiliary control on thebasis of a through image picked up by the image pickup device 12. Theimage pickup auxiliary control unit 42 performs an image pickupoperation on the basis of a result of the image pickup auxiliarycontrol. Since the image pickup device 12 is not able to pick up athrough image during the image pickup operation, the image pickupauxiliary control unit 42 stops the image pickup auxiliary controlduring the image pickup operation.

In this embodiment, the image pickup auxiliary control unit 42 performsimage pickup auxiliary control between an image pickup operation in thecontinuous image pickup mode and an image pickup operation. The imagepickup auxiliary control unit 42 can be configured to apply a result ofimage pickup auxiliary control used in the first image pickup operationof the continuous image pickup operation in the continuous image pickupmode to another image pickup operation of the continuous image pickupoperation.

The image pickup auxiliary control unit 42 includes, for example, an AFcontrol unit 51, an exposure control unit 52, an angle-of-view controlunit 53, a white balance (WB) control unit 54, a scene determinationunit 55 and an inter-frame noise reduction (NR) processing unit 56.

The AF control unit 51 performs an AF process that is one of the imagepickup auxiliary processes. For example, the AF control unit 51generates a control signal for driving a focus lens of the lens 10 onthe basis of image data output from the image pickup device 12 andinputs the generated control signal to the lens control unit. Morespecifically, the AF control unit 51 performs a contrast AF process, aphase difference AF process or another AF process on the basis of imagedata acquired in an arbitrary AF area on the imaging plane of the imagepickup device 12 to generate a control signal for driving a focus lensof the lens 10. For example, the AF control unit 51 has a singleautofocus mode (AF-S) in which AF is performed once when the releasebutton 15 a is half pushed, a continuous autofocus mode (AF-C) in whichAF is performed continuously while the release button 15 a is being halfpushed, or another autofocus mode.

When the AF control unit 51 performs the contrast AF process, itcomputes a contrast of an object image formed in an arbitrary AF area onthe imaging plane of the image pickup device 12 on the basis of imagedata output from the image pickup device 12 and supplies the lenscontrol unit of the lens 10 with a control signal for moving the focuslens. The AF control unit 51 controls the lens control unit of the lens10 to stop moving the focus lens in a position where the contrastbecomes the highest.

When the AF control unit 51 performs the phase difference AF process, itcompares the positions of images of the same object by image datadetected by a plurality of first focusing pixels arranged in anarbitrary AF area on the imaging plane of the image pickup device 12 andimage data detected by a plurality of second focusing pixels to detectan interval between the images. On the basis of the detected imageinterval, the AF control unit 51 computes an amount of shift between thecurrent position of the focus lens and the focus position. The AFcontrol unit 51 generates a control signal on the basis of the computedamount of shift and inputs the generated control signal to the lenscontrol unit of the lens 10 to control the lens control unit of the lens10 to move the focus lens to the focus position.

The exposure control unit 52 performs control of exposure conditions(exposure control) which is one of the image pickup auxiliary processes.For example, the exposure control unit 52 controls exposure conditionssuch as an amount of opening (diaphragm value) of the diaphragmmechanism of the lens 10, an open time of the shutter unit 11 (shutterspeed), and sensitivity of the image pickup device 12 (ISO speed) at thetime of image pickup. For example, the exposure control unit 52 setsexposure conditions such as a diaphragm value, a shutter speed and anISO speed on the basis of the operation of the operation unit 15.

Furthermore, the exposure control unit 52 performs a computation processfor exposure control on the basis of image data output from the imagepickup device 12. For example, the exposure control unit 52 computes thebrightness of an object on the basis of image data output from the imagepickup device 12. The exposure control unit 52 sets an exposure value inaccordance with an operation of the operation unit 15 and performs an AEprocess to set the exposure conditions such as a diaphragm value, ashutter speed, and an ISO speed at the time of image pickup in such amanner that the brightness of an object becomes equal to a presetexposure value. For example, the exposure control unit 52 computes thebrightness of an object on the basis of an area (AE area) of part of theimage data output from the image pickup device 12 to perform an AEprocess. Furthermore, for example, the exposure control unit 52 can beconfigured to compute the brightness of an object for each of the AEareas and integrate the brightnesses to perform an AE process.

The angle-of-view control unit 53 controls an angle of view which is oneof the image pickup auxiliary processes. The angle-of-view control unit53 recognizes the focal length of the image pickup lens on the basis ofan input from the lens control unit of the lens 10 and performs controlcorresponding to the recognized focal length. Furthermore, theangle-of-view control unit 53 generates a control signal for changingthe focal length of the image pickup lens of the lens 10 in accordancewith the operation of the operation unit 15 and inputs the generatedcontrol signal to the lens control unit of the lens 10.

The WB control unit 54 performs WB control which is one of the imagepickup auxiliary processes. The WB control unit 54 performs acomputation process for controlling a white balance on the basis ofimage data output from the image pickup device 12. The WB control unit54 controls a gain of each of RGB pixels of the image pickup device 12on the basis of a result of the computation process.

The scene determination unit 55 performs a scene determination which isone of the image pickup auxiliary processes. The scene determinationunit 55 determines a scene on the basis of image data output from theimage pickup device 12. The scene is, for example, a landscape, aperson, sports and a night view. For example, the scene determinationunit 55 is able to supply information indicative of the determined sceneto the exposure control unit 52 to cause the exposure control unit 52 toperform exposure control corresponding to the scene.

The inter-frame NR processing unit 56 performs an inter-frame NR processwhich is one of the image pickup auxiliary processes. The inter-frame NRprocessing unit 56 performs a noise reduction process of reducing noiseof image data by the known algorithm using image data of a plurality offrames output from the image pickup device 12. For example, theinter-frame NR processing unit 56 performs smoothing all of a pluralityof frames in such a manner that a difference in pixel value betweencoordinates of image data in a current frame and those of image data inits preceding frame becomes equal to or smaller than a preset value.

The recording control unit 43 includes an intermediate buffer forrecording a still image and a moving image temporarily. The recordingcontrol unit 43 records, e.g. a still image and a moving image capturedthrough an image pickup operation in the intermediate buffer one by one.The recording control unit 43 files the still image, the moving image,etc. recorded in the intermediate buffer and writes them to therecording medium M attached to the memory I/F 17. The filed still imageis a file in which a predetermined header is added to image data of thestill image. For example, data indicative of exposure conditions isrecorded in the header as tag data.

The display control unit 44 controls a display process to be performedby the display unit 16. For example, the display control unit 44supplies image data to the display unit 16 to control a screen to bedisplayed on the display device of the display unit 16. For example, thedisplay control unit 44 supplies the display unit 16 with a still imagegenerated by the image pickup device 12 through an image pickupoperation to cause the display unit 16 to display the still image.Furthermore, the display control unit 44 supplies the display unit 16with a through image read by the image pickup control unit 41 to causethe display unit 16 to display the through image. The display controlunit 44 causes the display unit 16 to display a through image in a framecycle of 60 fps, 120 fps or the like.

Moreover, the display control unit 44 generates OSD data for causing thedisplay unit 16 to make an on-screen display (OSD) including, e.g.various icons and characters, on the basis of different items of settinginformation and a state of the image pickup apparatus 1. For example,the display control unit 44 generates OSD data for displaying on thedisplay device of the display unit 16 an image pickup mode, differentitems of setting information, a battery remaining amount, the number ofshots and a time period for which image pickup is available in the imagepickup apparatus 1, an AF area and the like. The display control unit 44supplies the display unit 16 with image data on which OSD display basedon the OSD data is superimposed.

The state determination unit 45 recognizes different states of the imagepickup apparatus 1. For example, the state determination unit 45determines whether there is a light-shielded area on the through image.In accordance with an operating state of the shutter unit 11 when theimage pickup device 12 picks up a through image, the state determinationunit 45 determines whether the through image is a first through image ora second through image. For example, the state determination unit 45determines that the through image is a second through image if the rearcurtain 22 of the shutter unit 11 is being opened when the image pickupapparatus 12 picks up the through image.

Furthermore, the state determination unit 45 specifies a light-shieldedarea in the second through image. For example, the state determinationunit 45 specifies a light-shielded area in the second through image onthe basis of the position of the rear curtain 22 of the shutter unit 11when the second through image is picked up. For example, the statedetermination unit 45 also specifies an area in the second throughimage, which is darker than a preset value, as a light-shielded area.

FIGS. 4 and 5 are timing charts showing, from above, timing of imagepickup of through image, image pickup operation, operation of frontcurtain 21 of shutter unit 11, operation of rear curtain 22 of shutterunit 11, display of through image, and display of advice. FIG. 4 showsan example in which the image pickup apparatus 1 is in a normal statethat does not meet a specific condition. FIG. 5 shows an example inwhich the image pickup apparatus 1 is in a specific state that meets aspecific condition.

For example, when the image pickup apparatus 1 is in the normal state,the display control unit 44 controls the display unit 16 to display athrough image using a first through image. As shown in FIG. 4, thedisplay control unit 44 supplies first through images captured under thecontrol of the image pickup control unit 41, to the display unit 16 oneby one to cause the display unit 16 to display a through image. Since athrough image cannot be picked up by the image pickup device 12 duringthe image pickup operation, the display control unit 44 stops thedisplay unit 16 from displaying the through image during the imagepickup operation. When the rear curtain 22 of the shutter unit 11 iscompletely opened and the shutter unit 11 is opened after the imagepickup operation, the display control unit 44 supplies a first throughimage 74 to the display unit 16 to resume displaying the through imageon the display unit 16. After the image pickup operation, the displaycontrol unit 44 may display, for confirmation, a still image captured bythe image pickup operation on the display unit 16 for a given period oftime.

For example, as shown in FIG. 5, the display control unit 44 controlsthe display unit 16 to display a through image using an image includingat least a second through image and a still image on a specificcondition that the state of the image pickup apparatus 1 meets. Afterthe image pickup operation, the display control unit 44 may supply thedisplay unit 16 with a still image, which is captured by the imagepickup operation immediately after the image pickup operation iscompleted, as a through image to cause the display unit 16 to displaythe through image. For example, the display control unit 44 causes thedisplay unit 16 to display still images picked up by the image pickupoperation as through images for one frame or a plurality of frames. InFIGS. 4 and 5, a process from opening to closing of the rear curtain isemphasized in order to emphasize timing when a through image is resumed;however, needless to say, a phenomenon in which the through imagegradually disappears may occur even in a process from opening to closingof the front curtain. The slope from opening to closing of the frontcurtain in FIGS. 4 and 5 can be gentler. This state is not illustratedor described in detail for the sake of brevity because the point thattrackability is improved if display control has only to be carried outsuch that a half-open phenomenon may occur is substantially described inthis embodiment.

The specific condition represents a case where a user needs to confirm athrough image earlier. In other words, the state determination unit 45determines that the state of the image pickup apparatus 1 meets thespecific condition when the image pickup apparatus 1 is in a state thatrequires shortening a time period from when a still image is completelypicked up until image pickup auxiliary control is carried out (an imagepickup state in which a time lag becomes a problem). For example, thestate determination unit 45 recognizes a state of the image pickupapparatus 1 on the basis of a setting status of the image pickup controlunit 41 and image pickup auxiliary control unit 42, an output of the eyesensor 33, an output of the acceleration sensor 18 and the like, anddetermines that the image pickup apparatus 1 is in a specific state ifthe recognized state of the image pickup apparatus 1 meets the specificcondition.

The specific condition includes, for example, conditions that a userlooks through the EVF 32 in a continuous image pickup mode, a userfollows an object by panning, the mode of autofocus is an AF-C, theshutter speed is faster than a preset shutter speed, and the focallength of the image pickup lens of the lens 10 is greater than a presetfocal length. That is, the state determination unit 45 determines thatthe state of the image pickup apparatus 1 meets the specific conditionwhen the image pickup apparatus 1 corresponds to conditions, a userlooks through the EVF 32 in a continuous image pickup mode, a userfollows an object by panning, the mode of autofocus is an AF-C, theshutter speed is faster than a preset shutter speed, and the focallength of the image pickup lens of the lens 10 is greater than a presetfocal length.

The preset shutter speed is, for example, a second of time correspondingto 1/focal length which easily exerts an influence of a camera shake ora second of time corresponding to 2^(n)/focal length to which toleranceis added. In general, the preset shutter speed may be, for example,1/250 second at which an object that moves quickly is picked upfrequently.

The preset angle of view corresponds to, for example, a case where thefocal length is 70 mm for telescopic imaging. In addition, the presetangle of view can be set as a given focal length which makes itdifficult to frame a moving object.

For example, the state determination unit 45 may determine that theimage pickup apparatus is in the specific state when an object distanceis shorter than 60 cm of an object distance in the case ofshort-distance imaging such as macro photography.

An example of display by the display control unit 44 will now bedescribed. In FIG. 6, the upper-left image is an example of the stillimage 71, the upper-right and lower-left images are an example of thesecond through image 73 including a light-shielded area 72, and thelower-right image is an example of the first through image 74. Forexample, as shown in FIG. 6, the display control unit 44 supplies thedisplay unit 16 with the second through image 73 including alight-shielded area 72 to cause the display unit 16 to display thethrough image during a period from when the image pickup operation iscompleted until the rear curtain 22 of the shutter unit 11 is completelyopened. When the rear curtain 22 of the shutter unit 11 is completelyopened and the shutter unit 11 is opened, the display control unit 44supplies the first through image 74 to the display unit 16 to cause thedisplay unit 16 to display the through image.

The display control unit 44 includes, for example, an image processingunit 61 and an advice display unit 62.

The image processing unit 61 superimposes a superimposing image on thelight-shielded area of a second through image to generate a superimposedthrough image. The superimposed through image is an image including atleast the second through image and the superimposed through image. Asshown in FIG. 5, the display control unit 44 controls the display unit16 to display a through image using a still image and a superimposedthrough image generated by superimposing a superimposing image on animage including at least a second through image on a specific conditionthat the state of the image pickup apparatus 1 meets. For example, thedisplay control unit 44 supplies the display unit 16 with thesuperimposed through image to cause the display unit 16 to display thethrough image during a period from when the image pickup operation iscompleted until the rear curtain 22 of the shutter unit 11 is completelyopened. When the rear curtain 22 of the shutter unit 11 is completelyopened and the shutter unit 11 is opened, the display control unit 44supplies the first through image to the display unit 16 to cause thedisplay unit 16 to display the through image.

The image processing unit 61 superimposes other image data(superimposing image) on the light-shielded area of a second throughimage to generate a superimposed through image. For example, the imageprocessing unit 61 determines whether a second through image picked upby the image pickup device 12 and the last still image can besuperimposed.

For example, the image processing unit 61 computes a similarity betweenthe last still image and the second through image excluding thelight-shielded area. When the computed similarity is equal to or largerthan a preset value, the image processing unit 61 determines that thesecond through image and the last still image can be superimposed.

For example, the image processing unit 61 also extracts an object imagecommon to the last still image and the second through image excluding alight-shielded area by pattern matching. When there is an object imagecommon thereto, the image processing unit 61 determines that the secondthrough image and the last still image can be superimposed.

When the image processing unit 61 determines that the second throughimage and the last still image can be superimposed, it superimposes thelast still image on the light-shielded area of the second through imageto generate a superimposed through image.

In FIG. 7, the upper-left image is an example of the still image 71, theupper-right image is an example of the second through image 73 includinga light-shielded area 72, and the lower image is an example of asuperimposed through image 76 formed by superimposing the still image 71and the second through image 73. As shown in FIG. 7, the imageprocessing unit 61 extracts an image of the same area as thelight-shielded area 72 of the second through image 73 on the still image71, as a to-be-superimposed image 75. The image processing unit 61superimposes the extracted to-be-superimposed image 75 on thelight-shielded area 72 of the second through image 73 to generate asynthesized through image 76 including the second through image 73 andthe last still image 71.

Furthermore, for example, the image processing unit 61 corrects otherimage data and superimposes the corrected data on the light-shieldedarea of a second through image to generate a superimposed through image.In FIG. 8, the upper-left image is an example of the still image 71, thelower-left image is an example of the second through image 73 includinga light-shielded area 72, the upper-right image is an example of acorrected to-be-superimposed image 75, and the lower-right image is anexample of a superimposed through image 78 formed by superimposing thestill image 71 and the second through image 73. For example, as shown inFIG. 8, the image processing unit 61 extracts an object image 77 commonto the last still image 71 and the second through image 73 excluding thelight-shielded area 72, and computes a difference in position in thehorizontal-axis direction (longitudinal direction) of the object image77 between the images.

The image processing unit 61 corrects the to-be-superimposed image 75 inthe still image 71 using the computed difference. More specifically, theimage processing unit 61 corrects the position of the to-be-superimposedimage 75 to cancel the computed difference and, in other words, theimage processing unit 61 shifts the to-be-superimposed image 75 in thehorizontal-axis direction by the computed difference. The imageprocessing unit 61 superimposes the corrected to-be-superimposed image75 on the light-shielded area 72 of the second through image 73 togenerate a superimposed through image 78 of the correctedto-be-superimposed image 75 and the second through image 73. The imageprocessing unit 61 makes setting as to whether the to-be-superimposedimage 75 should be corrected in accordance with an operation of theoperation unit 15. On the basis of this setting, the image processingunit 61 determines whether the to-be-superimposed image 75 should becorrected.

The image processing unit 61 can be configured to generate asuperimposed through image 76 or a superimposed through image 78 byapplying image processing, such as blurring and monochromatization, tothe to-be-superimposed image 75 and then superimposing it to the secondthrough image 73.

The advice display unit 62 generates an image by superimposing asuperimposing image on an image including at least a second throughimage. For example, the advice display unit 62 generates an image bysuperimposing an advice display as a superimposing image on thelight-shielded area of the second through image. For example, as shownin FIG. 5, the display control unit 44 may control the display unit 16to display a through image using a still image and an image including anadvice display and a second through image on the specific condition thatthe state of the image pickup apparatus 1 meets. For example, thedisplay control unit 44 controls the display unit 16 to superimpose anadvice display on the second through image and display a through imageusing the second through image on which the advice display issuperimposed.

The advice display unit 62 generates an advice display that isinformation about photography. The advice display is useful informationthat is visually recognized by a user on the foregoing specificcondition and may include whatever information. For example, the advicedisplay unit 62 generates a display indicating whether an object can betracked or not, as an advice display.

For example, the advice display unit 62 determines that an object can betracked if a difference in position of the same object between imagedata of the current frame and that of the last frame is smaller than apreset threshold value. In other words, the advice display unit 62determines that an object can be tracked if a difference in position ofthe same object between image data of two frames picked up continuouslyis smaller than a preset threshold value. More specifically, the advicedisplay unit 62 determines that an object can be tracked if a differencein position of the same object between two second through images pickedup continuously is smaller than a preset threshold value. Furthermore,immediately after the image pickup operation, the advice display unit 62determines that an object can be tracked if a difference in position ofthe same object between a still image and a second through image pickedup immediately after the still image is picked up is smaller than apreset threshold value. On the basis of a result of this determination,the advice display unit 62 generates an advice display indicatingwhether the object can be tracked. On the basis of a result of thisdetermination, the advice display unit 62 generates an advice displayindicating whether the object can be tracked correctly.

The advice display unit 62 superimposes one or more advice displays onan image including at least a second through image. For example, theadvice display unit 62 superimposes an advice display on thelight-shielded area in the second through image.

The advice display unit 62 also updates statuses of advice displaysdisplayed on the light-shielded area in the second through image one byone. For example, the advice display unit 62 can be configured todetermine the visibility of an advice display in accordance with thesize of a light-shielded area specified by the state determination 45.More specifically, the advice display unit 62 increases the visibilityof an advice display according to the fact that the light-shielded areaof the second through image becomes narrower. For example, the advicedisplay unit 62 releases the advice display according to the fact thatthe shutter unit 11 is opened and the light-shielded area of the secondthrough image disappears.

The advice display unit 62 makes setting as to whether an advice shouldbe displayed in accordance with an operation of the operation unit 15.On the basis of this setting, the advice display unit 62 determineswhether an advice should be displayed.

In FIG. 9, the upper-left image is an example of the still image 71, theupper-right and lower-left images are an example of the second throughimage 73 including a light-shielded area 72, and the lower-right imageis an example of the first through image 74. For example, as shown inFIG. 9, the display control unit 44 supplies the display unit 16 with asecond through image 73 formed by superimposing the advice display 79 onthe light-shielded area 72 during a period from the image pickupoperation is completed until the rear curtain 22 of the shutter unit 11is completely opened, to cause the display unit 16 to display thethrough image. When the rear curtain 22 of the shutter unit 11 iscompletely opened and the shutter unit 11 is opened, the display controlunit 44 supplies the first through image 74 to the display unit 16 tocause the display unit 16 to display the through image.

An operation of the image pickup apparatus 1 according to one embodimentwill be described in detail with reference to FIGS. 10 and 11.

When the image pickup apparatus 1 is in an image pickup standby state,the main control unit 19 controls the image pickup device 12 to pick upa first through image 74 (step S11). The main control unit 19 suppliesthe first through image 74 to the display unit 16 to display the firstthrough image 74 on the display device of the display unit 16 (stepS12).

The main control unit 19 determines whether the release button 15 a ofthe operation unit 15 is half pushed (step S13) and, in other words, themain control unit 19 determines whether the operation unit 15 suppliesan operation to provide an instruction for image pickup auxiliarycontrol such as an AE process and an AF process. When the main controlunit 19 determines that the release button 15 a of the operation unit 15is half pushed (YES in step S13), it performs image pickup auxiliarycontrol such as an AE process and an AF process (step S14).

The main control unit 19 determines whether the release button 15 a ofthe operation unit 15 is all pushed (step S15) and, in other words, themain control unit 19 determines whether the operation unit 15 inputs anoperation to provide an instruction for image pickup operation. When themain control unit 19 determines that the release button 15 a of theoperation unit 15 is all pushed (YES in step S15), it stops displaying athrough image and performs an image pickup operation (step S16). In thiscase, the main control unit 19 operates the shutter unit 11, controlsthe image pickup device 12 to pick up a still image 71, files the stillimage and records the filed image on the recording medium M.

The main control unit 19 determines whether the state of the imagepickup apparatus 1 meets the foregoing specific condition (step S17).When the main control unit 19 determines that the state of the imagepickup apparatus 1 does not meet the specific condition (NO in stepS17), it determines whether the shutter 11 is opened by opening the rearcurtain 22 completely after the image pickup operation (step S18). Inother words, the main control unit 19 determines whether the shutterunit 11 is opened after the image pickup operation. The main controlunit 19 continues to perform a process of step S18 until the shutterunit 11 is opened.

When the main control unit 19 determines that the shutter unit 11 isopened (YES in step S18), it determines whether the process should becompleted (step S19). In other words, for example, the main control unit19 controls the operation unit 15 to operate the power button 15 b anddetermines whether the operation unit 15 inputs an instruction tocomplete the process. When the main control unit 19 determines that theprocess should be completed (YES in step S19), it turns off the power tocomplete the process. When the main control unit 19 determines that theprocess should not be completed (NO in step S19), it returns to stepS11.

When the main control unit 19 determines that the release button 15 a ofthe operation unit 15 is not half pushed (NO in step S13), or when themain control unit 19 determines that the release button 15 a is not allpushed (NO in step S15), it moves to step S19.

When the main control unit 19 determines that the state of the imagepickup apparatus 1 does not meet the specific condition as describedabove, it stops displaying the first through image 74 during a periodfrom after the image pickup operation is performed until the shutterunit 11 is opened.

When the main control unit 19 determines that the state of the imagepickup apparatus 1 meets the specific condition (YES in step S17), itsupplies the display unit 16 with the still image 71 captured throughthe image pickup operation in step S16, as a through image for apredetermined frame, to cause the display unit 16 to display the throughimage (step S21).

The main control unit 19 determines whether the shutter unit 11 isopened after the image pickup operation (step S22). When the maincontrol unit 19 determines that the shutter unit 11 is opened after theimage pickup operation (YES in step S22), it moves to step S19.

When the main control unit 19 determines that the shutter unit 11 is notopened after the image pickup operation (NO in step S22), it controlsthe image pickup device 12 to pick up the second through image 73 (stepS23). The main control unit 19 supplies the second through image 73 tothe display unit 16 to cause the display unit 16 to display the throughimage (step S24), and moves to step S22.

The main control unit 19 continues to perform the processes of steps S23and S24 until the shutter unit 11 is opened after the image pickupoperation.

According to the foregoing configuration, the display control unit 44 ofthe main control unit 19 causes the display unit 16 to display the stillimage 71 as a through image for a predetermined frame immediately afterthe image pickup operation is completed. The display control unit 44causes the display unit 16 to display a second through image 73including a light-shielded area 72, which is picked up by the imagepickup device 12, during a period from when the image pickup operationis completed until the shutter unit 11 is opened. When the shutter unit11 is opened, the display control unit 44 causes the display unit 16 todisplay the first through image 74 picked up by the image pickup device12.

Therefore, when the image pickup apparatus 1 meets the specificcondition, it is able to cause a through image to be displayed using thestill image 71 and the second through image 73 during a period from whenthe image pickup operation is completed until the shutter unit 11 isopened. In other words, since the image pickup apparatus 1 is able toprevent display of a through image from being stopped with timing whenthe shutter unit 11 is not completely opened after the image pickupoperation is completed, the possibility that a user could lose sight ofan object can be lowered. It is thus possible to provide a moreconvenient image pickup apparatus and a method for controlling the imagepickup apparatus.

Another operation of the image pickup apparatus 1 according to oneembodiment will be described in detail below with reference to FIGS. 10and 12.

As described above, the main control unit 19 determines whether thestate of the image pickup apparatus 1 meets the foregoing specificcondition (step S17). When the main control unit 19 determines that thestate of the image pickup apparatus 1 meets the specific condition (YESin step S17), it moves to step S31 in FIG. 12 to supply the display unit16 with a still image 71 captured by the image pickup operation of stepS16 as a through image for a predetermined frame and cause the displayunit 16 to display the through image (step S31).

The main control unit 19 determines whether the shutter unit 11 isopened after the image pickup operation (step S32). When the maincontrol unit 19 determines that the shutter unit 11 is opened (Yes instep S32), it moves to step S19 in FIG. 10.

When the main control unit 19 determines that the shutter unit 11 is notopened (No in step S32), it causes the image pickup device 12 to pick upa second through image 73 (step S33).

The main control unit 19 compares the still image 71 captured throughthe last image pickup operation and the second through image 73 capturedin step S33 (step S34). On the basis of a result of the comparison, themain control unit 19 determines whether the second through image 73picked up by the image pickup device 12 and the last still image 71 canbe superimposed (step S35).

When the main control unit 19 determines that the second through image73 and the last still image 71 cannot be superimposed (No in step S35),it supplies the second through image 73 to the display unit 16 to causethe display unit 16 to display the through image (step S36) and returnsto step S32.

When the main control unit 19 determines that the second through image73 and the last still image 71 can be superimposed (Yes in step S35), itdetermines whether a to-be-superimposed image 75 in the still image 71should be corrected (step S37).

When the main control unit 19 determines that the to-be-superimposedimage 75 should not be corrected (No in step S37), it superimposes theto-be-superimposed image 75 on a light-shielded area 72 of the secondthrough image 73 to generate a superimposed through image 76 of thesecond through image 73 and the last still image 71 (step S38). The maincontrol unit 19 supplies the display unit 16 with the superimposedthrough image 76 generated in step S38 to cause the display unit 16 todisplay the through image (step S39), and returns to step S32.

When the main control unit 19 determines that the to-be-superimposedimage 75 should be corrected (Yes in step S37), it computes a differencein position in the horizontal-axis direction of an object image 77common to the second through image 73 and the last still image 71 (stepS40). The main control unit 19 corrects the to-be-superimposed image 75on the basis of the difference computed in step S38 (step S41). The maincontrol unit 19 superimposes the corrected to-be-superimposed image 75on a light-shielded area of the second through image 73 to generate asuperimposed through image 78 of the corrected to-be-superimposed image75 and the second through image 73 (step S42). The main control unit 19supplies the display unit 16 with the superimposed through image 78generated in step S42 to cause the display unit 16 to display thethrough image (step S43), and returns to step S32.

The main control unit 19 continues to perform processes of steps S33 toS43 until the shutter unit 11 is opened after the image pickupoperation.

According to the above processes of steps S38 and S39, the displaycontrol unit 44 of the main control unit 19 causes the display unit 16to display the superimposed through image 76 during a period from whenthe image pickup operation is completed until the shutter unit 11 isopened. The display control unit 44 causes the display unit 16 todisplay the first through image after the shutter unit 11 is opened.

Therefore, when the image pickup apparatus 1 meets the specificcondition, it is able to cause a through image to be displayed using thestill image 71 and the superimposed through image 76 during a periodfrom when the image pickup operation is completed until the shutter unit11 is opened. In other words, since the image pickup apparatus 1 is ableto prevent display of a through image from being stopped with timingwhen the shutter unit 11 is not completely opened after the image pickupoperation is completed, the possibility that a user could lose sight ofan object can be lowered. It is thus possible to provide a moreconvenient image pickup apparatus and a method for controlling the imagepickup apparatus.

Furthermore, according to the above processes of steps S40 to S43, thedisplay control unit 44 of the main control unit 19 corrects theto-be-superimposed image 75 of the still image 71 on the basis of adifference in position in the horizontal-axis direction of the objectimage 77 common to the second through image 73 and the last still image71 and superimposes the to-be-superimposed image 75 on thelight-shielded area of the second through image 73 to generate asuperimposed through image 78. The image pickup apparatus 1 causes thedisplay unit 16 to display the superimposed through image 78 and thendisplay the through image during a period from when the image pickupoperation is completed until the shutter unit 11 is opened, thus makingit possible to prevent the through image from being displayedinaccurately

Another operation of the image pickup apparatus 1 according to oneembodiment will be described in detail below with reference to FIGS.10-13.

As described above, the main control unit 19 determines whether thestate of the image pickup apparatus 1 meets the foregoing specificcondition (step S17). When the main control unit 19 determines that thestate of the image pickup apparatus 1 meets the specific condition (YESin step S17), it moves to step S51 in FIG. 13 to supply the display unit16 with a still image 71 captured by the image pickup operation of stepS16 as a through image for a predetermined frame and cause the displayunit 16 to display the through image (step S51).

The main control unit 19 determines whether the shutter unit 11 isopened after the image pickup operation (step S52).

When the main control unit 19 determines that the shutter unit 11 is notopened after the image pickup operation (NO in step S52), it causes theimage pickup device 12 to pick up a second through image 73 (step S53).The main control unit 19 supplies the second through image 73 to thedisplay unit 16 to cause the display unit 16 to display the throughimage (step S54).

The main control unit 19 determines whether an advice display 79 shouldbe superimposed on the second through image 73 (step S55). When the maincontrol unit 19 determines that an advice display 79 should not besuperimposed on the second through image 73 (No in step S55), it returnsto step S52.

When the main control unit 19 determines that an advice display 79should not be superimposed on the second through image 73 (YES in stepS55), it determines whether the advice display 79 is being displayed(step S56). In other words, the main control unit 19 determines whetheran advice 79 has already been superimposed on the second through image73 and displayed.

When the main control unit 19 determines that an advice display 79 isnot being displayed (NO in step 56), it generates an advice display 79(step S57). The main control unit 19 superimposes the generated advicedisplay 79 on the second through image 73 and displayed (step S58), andreturns to step S52.

When the main control unit 19 determines that an advice display 79 isbeing displayed (YES in step 56), it updates the display state of theadvice display 79 (step S59) and returns to step S52.

The main control unit 19 continues to perform the processes of steps S53to S59 until the shutter unit 11 is opened after the image pickupoperation.

When the main control unit 19 determines that the shutter unit 11 isopened after the image pickup operation (YES in step S52), it releasesthe advice display 79 (step S60) and moves to step S19 in FIG. 10.

According to the foregoing configuration, when the state of the imagepickup apparatus 1 meets the specific condition, the display controlunit 44 of the main control unit 19 causes the display unit 16 todisplay the still image 71 immediately after the image pickup operationis completed. The display control unit 44 causes the display unit 16 todisplay the second through image 73, which is formed by superimposingthe advice display 79 on the light-shielded area 72 and picked up by theimage pickup device 12, during a period from when the image pickupoperation is completed until the shutter unit 11 is opened. When theshutter unit 11 is opened, the display control unit 44 causes thedisplay unit 16 to display the first through image 74 picked up by theimage pickup device 12. The present invention is not limited to theperiod from when the image pickup operation is completed until theshutter unit 11 is opened. In order to increase the visibility of anadvice, the shutter unit can be opened, or the advice can be output fora while. If the advice can be recognized by intuition by patternrecognition, such as OK/NG determination and a histogram, it may becanceled soon to avoid a complicated operation. If a limited time and adisplay space are effectively used in addition to a period of time forwhich the closing of the shutter unit can be seen to allow a user toshift to a next action quickly, the object of the present invention canbe attained.

Therefore, the image pickup apparatus 1 is so configured that a user canvisually recognize an advice display that is information aboutphotography with timing when the shutter unit 11 is not completelyopened. As a result, there can be provided a more convenient imagepickup apparatus and a method for controlling the image pickupapparatus.

An example of making a display indicating whether an object can betracked or not has been described above as an example of the advicedisplay 79; however, the present invention is not limited to thisexample. The advice display unit 62 can be configured to generate, asthe advice display 79, a display of the histogram of the still image 71picked up by the image pickup device 12, a display indicating a positionof the AF area in the still image 71, a display indicating the remainingamount of the intermediate buffer in the recording control unit 43, thenumber of images that can continuously be picked up as many as possible,an alarm about a camera shake, a thumbnail of the still image 71 thathas already been picked up, and the like.

FIG. 14 shows an example of displaying, as the advice display 79, adisplay of the histogram of the still image 71 picked up by the imagepickup device 12 and a display indicating a position of the AF area inthe still image 71. FIG. 15 shows an example of displaying, as theadvice display 79, a thumbnail of the still image 71 that has alreadybeen picked up. The advice display unit 62 makes setting as to whatcontent is displayed as the advice display 79 in accordance with aninput operation by the operation unit 15. On the basis of this setting,the advice display unit 62 determines a content to be displayed as theadvice display 79.

Furthermore, for example, the advice display unit 62 can be configuredto determine a type of the advice display 79 to be displayed, accordingto the specific condition that the state of the image pickup apparatus 1meets. For example, the advice display unit 62 includes a memory forstoring, e.g. a table to which the type of the advice display 79 iscaused to correspond for each specific condition. The advice displayunit 62 specifies one specific condition in accordance with the state ofthe image pickup apparatus 1 from the table and determines a content tobe displayed as the advice display 79 according to the specifiedspecific condition.

In the foregoing embodiment, furthermore, the advice display unit 62 isso configured to release the advice display 79 when the shutter unit 11is opened; however, the present invention is not limited to thisconfiguration. The advice display unit 62 can be configured to displaythe advice display 79 for a preset time period after the advice display79 is displayed first.

The advice display unit 62 can be configured to display the advicedisplay 79 for a preset time period after the advice display 79 isdisplayed first and increase the visibility of the advice display 79according to the elapsed time.

In the foregoing embodiment, the image pickup apparatus 1 is configuredto include the lens 10; however, the present invention is not limited tothis configuration. The image pickup apparatus 1 is configured toinclude a detachable mount lens in place of the lens 10.

Not only the functions of the foregoing embodiments are carried out byhardware, but also the programs describing the functions using softwarecan be read in a computer and executed. The functions can also becarried out by choosing one of software and hardware appropriately.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details and representative embodiments shownand described herein. Accordingly, various modifications may be madewithout departing from the spirit or scope of the general inventiveconcept as defined by the appended claims and their equivalents.

What is claimed is:
 1. An image pickup apparatus comprising: an imagepickup device including an imaging plane on which imaging pixels arearranged; a shutter unit which adjusts an amount of light incident uponthe imaging plane; an image pickup control unit which drives the shutterunit and picks up a still image by the image pickup device, captures afirst through image by the image pickup device when the shutter unit isopened, and picks up a second through image including a light-shieldedarea by the image pickup device, the light-shielded area being formed byshielding part of light incident upon the imaging plane by the shutterunit when the shutter unit is partly light-shielded; and a displaycontrol unit which causes a display device to display a through imageusing at least the first through image and the second through image;wherein the display control unit causes the display device to display athrough image using an image including at least the second through imageduring a period from when the still image is completely picked up untilthe shutter unit is opened.
 2. The image pickup apparatus according toclaim 1, wherein the display control unit causes the display device todisplay a through image using the still image and an image including atleast the second through image during a period from when the still imageis completely picked up until the shutter unit is opened.
 3. The imagepickup apparatus according to claim 2, wherein the display control unitcauses the display device to display the still image as a through imageto correspond to a preset frame number immediately after the still imageis completely picked up.
 4. The image pickup apparatus according toclaim 1, further comprising a state determination unit which recognizesa state of the image pickup apparatus to determine whether therecognized state meets a preset specific condition, and wherein when thestate determination unit determines that the recognized state meets thepreset specific condition, the state determination unit causes thedisplay device to display a through image using an image including atleast the second through image during a period from when the still imageis completely picked up until the shutter unit is opened, and when thestate determination unit determines that the recognized state does notmeet the preset specific condition, the state determination unit doesnot cause the display unit to display a through image using an imageincluding the second through image.
 5. The image pickup apparatusaccording to claim 4, wherein the state determination unit determinesthat the state of the image pickup apparatus meets the specificcondition when the image pickup apparatus is set in a continuous imagepickup mode to pick up still images continuously.
 6. The image pickupapparatus according to claim 4, wherein the state determination unitdetermines that the state of the image pickup apparatus meets thespecific condition when an autofocus mode is set in a continuousautofocus mode.
 7. The image pickup apparatus according to claim 4,wherein the state determination unit determines that the state of theimage pickup apparatus meets the specific condition when a shutter speedthat is higher than a preset shutter speed.
 8. The image pickupapparatus according to claim 4, further comprising an image pickup lenswhose focal length is variable, wherein the state determination unitdetermines that the state of the image pickup apparatus meets thespecific condition when the focal length of the image pickup lens islonger than a preset focal length.
 9. The image pickup apparatusaccording to claim 4, further comprising: an electronic viewfinder whichdisplays a screen under control of the display control unit; and an eyesensor which senses whether an object is present close to the electronicviewfinder, wherein the state determination unit determines that thestate of the image pickup apparatus meets the specific condition whenthe eye sensor senses that an object is present close to the electronicviewfinder.
 10. The image pickup apparatus according to claim 4, furthercomprising an acceleration sensor which senses a variation inacceleration to sense whether that panning is performed, wherein thestate determination unit determines that the state of the image pickupapparatus meets the specific condition when the acceleration sensorsenses that panning is performed.
 11. A method for controlling an imagepickup apparatus including an image pickup device including an imagingplane on which imaging pixels are arranged, and a shutter unit whichadjusts an amount of light incident upon the imaging plane, the methodcomprising: driving the shutter unit and picking up a still image by theimage pickup device; capturing a first through image by the image pickupdevice when the shutter unit is opened; picking up a second throughimage including a light-shielded area by the image pickup device, thelight-shielded area being formed by shielding part of light incidentupon the imaging plane by the shutter unit when the shutter unit ispartly light-shielded; causing a display device to display a throughimage using at least the first through image and the second throughimage; and causing the display device to display a through image usingan image including at least the second through image during a periodfrom when the still image is completely picked up until the shutter unitis opened.
 12. A non-transitory computer-readable medium storing acomputer program for an image pickup apparatus including an image pickupdevice including an image plane on which imaging pixels are arranged,and a shutter unit which adjusts an amount of light incident upon theimaging plane, the program comprising: driving the shutter unit andpicking up a still image by the image pickup device; capturing a firstthrough image by the image pickup device when the shutter unit isopened; picking up a second through image including a light-shieldedarea by the image pickup device, the light-shielded area being formed byshielding part of light incident upon the imaging plane by the shutterunit when the shutter unit is partly light-shielded; causing a displaydevice to display a through image using at least the first through imageand the second through image; and causing the display device to displaya through image using an image including at least the second throughimage during a period from when the still image is completely picked upuntil the shutter unit is opened.